BMP-7过表达的骨髓间充质干细胞对矽肺的拮抗作用及相关机制研究

Silicosis is the most serious occupational disease for laborers,which has the highest incidence rates, and there is no effective treatment now.Bone marrow mesenchymal stem cells (BMSCs), as an ideal target for cell- and gene-therapy, have most possible application foreground. Previous studies published by our research group have found that bone morphogenetic protein-7 (BMP-7) had effective antagonistic effect on silicosis fibrosis. In this research, technologies including Transwell co-culture system, Micro CT for lung tissue scanning in vivo, small animal in vivo imaging system, two-photon microscopy and antibody chip technology are used, and the silicosis model is established through dynamic dust exposure in rats in order to investigate the inhibitory effect of BMP-7 gene overexpression BMSCs (BMP-7-BMSCs) intervention on rats fibrosis. In vitro, the lung tissues co-culture systems in both normal with no injury and silicosis groups are set to induce the differentiation of BMSCs to alveolar epithelial cells. Furthermore, the implantation and differentiation, input time window, paracrine effects of BMP-7-BMSCs in vivo are systemically studied to explore the protective mechanisms of BMP-7-BMSCs transplantation on quartz-induced fibrosis. The research would provide innovative way for the further exploration of effective strategieson silicosis treatment and improvement of patients' life quality.

矽肺是我国发病最多、对劳动者健康危害最严重的职业病，尚无有效的治疗方法。研究显示骨髓间质干细胞（BMSCs）是最具应用前景的细胞与基因治疗的理想靶细胞。课题组前期研究发现骨形态发生蛋白-7（BMP-7）具有明显的拮抗矽肺纤维化作用。本项目利用Micro CT 活体肺组织扫描、小动物活体成像系统、Transwell共培养体系、双光子显微镜、抗体芯片等技术，通过动态染尘的方式制备大鼠矽肺模型，观察BMP-7过表达BMSCs（BMP-7-BMSCs）干预对大鼠肺纤维化的抑制作用；建立体外非接触无损伤大鼠肺组织和矽肺组大鼠肺组织共培养模型，观察BMSCs的分泌功能及向肺泡上皮细胞分化情况。系统研究BMP-7过表达BMSCs在体内的植入和分化、输入时间窗、旁分泌效应，探讨BMP-7过表达BMSCs移植对石英致大鼠肺纤维化的保护机制。该研究为进一步探索防治矽肺的有效途径，提高患者生活质量提供新的思路。

矽肺是由于生产过程中长期吸入游离二氧化硅粉尘引起的以肺组织弥漫性纤维化为主的全身性疾病。虽然矽肺的病因明确，但发病机制尚未完全清楚。越来越多证据表明，肺泡上皮细胞在肺组织损伤修复中发挥着至关重要的作用。肺泡上皮细胞的功能受损和修复能力丧失是矽肺纤维化发展的重要机制。骨髓间充质干细胞（BMSCs）是一种具有多向分化潜能的成体干细胞，在组织损伤修复中发挥免疫调节、细胞保护及抗纤维化的作用。目前为止，BMSCs拮抗石英诱导的肺纤维化作用及机制尚不清楚。课题组前期研究已证实骨形态发生蛋白-7(BMP-7)能抑制石英诱导的肺纤维化。本研究采用细胞移植与基因治疗相结合的方法，将BMSCs和BMP-7过表达的BMSCs（BMP-7-BMSCs）移植入大鼠体内，分别从体内实验及体外实验观察BMSCs和BMP-7-BMSCs在肺脏的分布、分化及旁分泌的情况，初步探讨BMSCs和BMP-7-BMSCs移植对石英诱导大鼠肺纤维化的抑制作用机制。研究发现：① BMSCs能够定向迁移至石英损伤的肺组织，BMSCs具有归巢作用；② BMSCs可以拮抗石英诱导大鼠的肺纤维化，BMSCs未直接分化成肺泡上皮细胞参与肺组织修复，可能通过旁分泌的途径分泌细胞因子HGF、KGF及BMP-7，下调TGF-β1与TNF-α的表达，从而促进肺泡上皮细胞的增殖，抑制石英诱导大鼠的肺纤维化进程；③ 与BMSCs相比，BMP-7-BMSCs拮抗石英诱导大鼠的肺纤维化、减轻肺泡上皮损伤的作用更显著。BMP-7-BMSCs可能通过旁分泌HGF及KGF，下调TGF-β1与TNF-α的表达，促进肺泡上皮细胞增殖，拮抗石英诱导的肺纤维化；④ Micro CT能够评价石英诱导的大鼠矽肺纤维化程度并反映BMSCs对肺纤维化的拮抗作用。该项研究为寻找潜在的矽肺治疗有效途径提供了理论依据。